NSW Council for Civil Liberties president Stephen Blanks said he was concerned about the possibility of "function creep" with more and more law enforcement agencies pushing to use secret warrants.

"It's always disturbing when powers are given to agencies for terrorism, then another agency says they would like to use those for something else," he said.

"That is a problem with not drawing a line in the sand that says some powers are just too dangerous to be given to government agencies."

Article: Call for secret search warrants lashed by civil libertarians, security experts

Source: Australian Financial Review